Thelong-termobjectiveofthisresearchprojectistodevelop?forthefirsttime?competitive antagonists(i.e.reversalagents)forgeneralanesthetics.Thiswouldallowclinicianstoreverseanesthesiaon demandandassistscientistsadvancetheirresearchprograms.Currently,acriticalobstacletodeveloping suchantagonistsforanestheticsthatactviatheGABAAreceptoristhattherearenostrategiesfordesigning competitiveligandsthatcanbindtothereceptor?sanestheticbindingsiteswithoutenhancingthereceptor?s functionandthusproducinganesthesia.Thespecificgoalofthisresearchproposalistoovercomethat obstaclebydiscoveringthefundamentalprinciplesandestablishingthedrugdesignstrategiesthatare necessarytodevelopanestheticcompetitiveantagonistsforclinicalandresearchuse. Wehavediscoveredthatbymodifyingakeyregionofitsmolecularstructure,thehighlyefficacious anestheticetomidatecanbetransformedintoananesthetic-selectivecompetitiveantagonistattheGABAA receptorthatacceleratesinvivoanestheticrecovery.Thisdiscoveryprovidesimportantcluesregardingthe changesthatoccurintheGABAAreceptor?sanestheticbindingsitesasitisomerizesfromclosedtoopen,and suggestsanovelstrategyfordesigninganestheticreversalagentsusingexistinganestheticsasmolecular templates.Aim1istobetterunderstandwhysuchmodificationsdramaticallyreduceetomidate?sbinding selectivityfortheopenstateoftheGABAAreceptor,almostcompletelyabolishitsintrinsicefficacyforreceptor activation,andtransformitintoananesthetic-specificcompetitiveantagonistatthereceptor.Itwillalsotest whetheranaloguescontainingthismodificationantagonizethereceptoractionsofotheranestheticsbesides propofolandetomidate.Aim2istoquantifythebindingselectivityoftheseetomidateanaloguesforthetwo differentclassesofanestheticbindingsiteslocatedbetweendifferentreceptorsubunitsusingphotoaffinity labelingtechniques.Aim3istodefinethebehavioralactionsoftheseanaloguesinratsandtestwhetherone withverylowefficacycanacceleraterecoveryfromhypnosisproducedbydifferentanesthetics. Currently,recoveryfromananesthetic'sactionsmustoccurasapassiveprocesswhosetimecourse isdictatedbytherateofanestheticdrugclearanceratherthantheactualclinicalneed.Theavailabilityof generalanestheticcompetitiveantagonistswouldhaveanenormousimpactonpatientcarebyallowing anestheticemergencetobeactivelymanagedandpreciselycontrolled.Itwouldimprovepatientsafetyand challengecurrentpracticemodelsofanesthesiacarebyallowingpotentiallydeadlysideeffectssuchas respiratorydepressiontobereversedimmediatelyandon-demand.Itwouldalsoadvancescientific researchbyhelpinginvestigatorstolocatenovelsitesofanestheticaction,testforthepossibleexistenceof endogenousligandsforanestheticbindingsites,rationallydesignnewexogenousligandsforthesesites, anddefinetherolethatparticulartargetsplayinproducingvariousinvitroandinvivoanestheticactions.